Food container having enhanced biodegradability, heat-stability and absorbability

ABSTRACT

A paper laminate provided for a food container includes a substrate paper or paper sheet, and at least a fibrous or fabric absorbent layer consisting of a biodegradable polymer selected from the group consisting of polylactic acid (PLA), polyhdroxyalkanoate (PHA), and polyhydroxy butyrate-co-valerate (PHBV), and a reinforcing polymer which includes a thermobondable polymer of polyethylene; with the absorbent layer formed, coated, bonded or adhered on the substrate paper to form a moisture and oil absorbable layer inside the food container to absorb moisture and oil in the food container for enhancing the food taste and quality, and also to provide a heat-durable and biodegradable food container.

BACKGROUND OF THE INVENTION

A conventional food box may be made by coating a polyethylene (PE) filmor other films on a paper sheet to form a water-proof box. When such afilm-coated paper box is provided for storing heated food such as friedrice, the moisture existing in the food will be vaporized and thencondensed to cause the food sticky, thereby deteriorating the foodquality or taste.

If such a film-coated paper box is provided for storing fried chicken orother oily foods, the excess oil as drained from the food will not beabsorbed by the paper box and may be accumulated on the food to be fedinto the eater's body to be hazardous to her or his body weight controlor even harmful to their cardiovascular system.

The PE-coated paper box served for food container may be water repellentand heat durable. However, the conventional polyethylene is notbiodegradable and may cause environmental problem when discarded.

For environmental protection reason, the polylactic acid (PLA)-coatedpaper box may be served as food or drink container to be biodegradableafter being used.

Even polylactic acid (PLA) is biodegradable, it however hasdisadvantages of low resistance to condition of high heat and humidity,thereby still being not satisfactory to be a food or drink container.

The present invention has found the drawbacks of conventional foodcontainer and invented the present food container, which isbiodegradable, thermally stable and moisture or oil absorbable.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a food containerfoldably formed by a paper laminate including a substrate paper or papersheet, and at least a fibrous or fabric absorbent layer consisting of athermobondable polymer including polyethylene (PE) and a biodegradablepolymer selected from the group consisting of polylactic acid (PLA),polyhdroxyalkanoate (PHA), and polyhydroxy butyrate-co-valerate (PHBV)formed, coated, bonded or adhered on the substrate paper to form amoisture and oil absorbable layer inside the food container to absorbmoisture and oil in the food container for enhancing the food taste andquality, and also to provide a heat-durable and biodegradable foodcontainer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional drawing showing a food container for storing friedrice in accordance with the present invention.

FIG. 2 is a partial cross-sectional drawing as viewed from line 2-2 ofFIG. 1.

FIG. 3 is a partial cross-sectional drawing as viewed from 3-3 directionof FIG. 1.

FIG. 4 is a sectional drawing of the paper laminate for forming a drinkcontainer in accordance with the present invention.

DETAILED DESCRIPTION

As shown in FIGS. 1-3, the present invention of food container,especially for storing foods F such as fried rice or fried chickentherein, comprises a food container foldably made of a paper laminate10.

The paper laminate 10 of the present invention comprises: a papersubstrate (or base paper sheet) 1, and a fibrous absorbent layer 2formed on an inside surface of the paper substrate 1 adjacent orcontiguous to the food F as stored in the food container, and aprotective layer 3 formed on an outer surface of the paper substrate 1,with the protective layer 3 exposed to the environment or thesurroundings of the food container.

The paper substrate 1 may be selected from a paper, a paper sheet, apaper board, etc.

The fibrous absorbent layer 2 comprises a fiber layer, non-woven orwoven fabric made of multi-component fiber, which includes: abiodegradable polymer, and a reinforcing polymer including athermobondable polymer.

The thermobondable polymer and the biodegradable polymer are co-extrudedto produce the multi-component fiber, which is then processed as afabric, including non-woven fabric or woven fabric. A conventionalco-extrusion or lamination or any other processes may be provided forforming the fabric of the present invention, not limited in thisinvention.

The biodegradable polymer may be selected from polylactic acid (PLA),polyhydroxyalkanoate (PHA), polyhydroxy butyrate-co-valerate (PHBV),Copoly-L-Lactide (CPLA), and other suitable biodegradable polymers.

The thermobondable polymer includes polyethylene (PE), polypropylene(PP) or any other thermobondable polymers. The thermobondable polymermay also include heat adhesive or heat bondable adhesive for thermallybonding the biodegradable polymer as above-mentioned in order to formthe multi-component or bi-component fiber, which is then furtherprocessed as non-woven or woven fabric to be the fibrous absorbent layer2 as formed on the paper substrate 1 of the present invention.

The thermobondable polymer, e.g., polyethylene (PE) may be wellthermally bonded with the biodegradable polymer, e.g., polylactic acid(PLA) to produce the fibrous absorbent layer 2, which is then formed onthe paper substrate 1 to obtain the paper laminate 10 of a foodcontainer of the present invention.

The fibrous absorbent layer 2 may be thermally bonded on the papersubstrate 1, preferably by the aid of a heat-bondable biodegradableadhesive including an adhesive of PLA blended with PE. Such aheat-bondable biodegradable adhesive may be coated or pre-formed on thepaper substrate 1 by any conventional processes, not limited in thepresent invention. Or, the adhesive may be formed as an adhesive layeror binder coated or formed on the paper substrate 1, before beingfurther coated with the fibrous absorbent layer 2 thereon.

The thermobondable polymer, such as polyethylene, may also be modifiedto be biodegradable, even the production cost thereof may be increased.

The reinforcing polymer including a thermobondable polymer is providedfor reinforcing the heat stability and moisture resistance of thebiodegradable polymer.

The outer protective film layer 3 may be made by blending polyethylenewith biodegradable polylactic acid to have the properties forbiodegradation and heat stability as well as moisture resistance(water-proof property) so that the food container of the presentinvention may be totally biodegraded after being used.

Of course, other water-proof or heat durable polymers, or biodegradablepolymers may also be selected for making the outer protective layer 3 ofthe present invention.

The multi-component fiber may also be directly formed (to serve as theabsorbent layer 2) on the paper substrate 1 without being primarilyprocessed to be a non-woven or woven fabric. For instance, themulti-component fiber (including PE and PLA fibers) may be directlythermally bonded or bonded by adhesive to the paper substrate 1.

The thermobondable polymer (e.g., PE) and the biodegradable polymer(e.g., PLA) may be blended in a ratio of 50:50, but not limited in thisinvention.

The fibrous absorbent layer 2 formed on the paper substrate 1 may befurther perforated to increase its capillary absorptive property.

When the food container is constructed by the paper laminate 10 as shownin FIG. 1 in accordance with the present invention, a hot food F such asfried rice just taken-away from a restaurant may vaporize its steamvapor V upwardly to be absorbed into the fibrous absorbent layer 2bonded to the paper substrate 1 of the top cover C of the food containeras illustrated in FIG. 2 to minimize the moisture content in the foodcontainer to prevent a dew condensation after the steam vapor beingcondensed and drained to the fried rice to thereby prevent the rice frombeing sticky and to maintain its “fresh” taste or quality of the food.

Meanwhile, the oil drops O as drained downwardly from the fried rice maybe capillarily penetrated and absorbed by the fibrous absorbent layer 2on the paper substrate 1 of the bottom container B as shown in FIG. 3,to minimize the oil accumulated in the voids or on the surface of therice. Therefore, the eater may reduce oil “dosage” into her or his body(stomach and bowels) to be beneficial for her or his health includingcardiovascular system and body weight control.

If the fried rice as above-mentioned is substituted with fried chickenor other oily foods, the fibrous absorbent layer 2 of the presentinvention may also help absorb the excess oil as contained in (or on)the oily foods, to be helpful for the eater's health.

The present invention may not only improve the poor heat stability ordurability of the biodegradable polylactic acid (PLA) by incorporatingtherein with polyethylene (PE), but also improving the poorbiodegradability of the non-biodegradable PE by incorporating PLAtherein. Both PE and PLA are made as oil and moisture absorbable fibersor fabric, thereby enhancing their absorbability of oil and moisture tokeep a well food taste or quality, and also to serve an oil-minimizedfood beneficial for eater's health.

The biodegrable polymer, e.g., the PLA, may be further incorporatedtherein with nano silver or any other anti-bacterial ingredient toenhance the food preserving and anti-bacterial property of the presentinvention.

If the oil or moisture absorption requirement is not so critical ornecessary for making the food container in accordance with the presentinvention, the fibrous absorbent layer 2 as aforementioned may besimplified or modified to be a thermobondable biodegradable film layer 3as shown in FIG. 4 to be formed or coated on both inner and outsidelayers of the “core layer” of paper substrate 1 to serve as a drinkcontainer.

Or, such a thermobondable biodegradable layer 3 may be served as aprotective layer 3 to be formed or adhered on an outer surface of thepaper substrate 1 as shown in FIGS. 1-3.

The word “Food” of the title of the invention, “Food Container”, may becomprehensively explained to be a food, a drink or the like. The paperlaminate 10 may be formed as food containers with diversified shapes, ordesigns to be a box, a case, a bowl, a bag, a tray, a cup, etc.

The present invention may be further modified without departing from thespirit and scope of the present invention.

1. A food container made of a paper laminate comprising: a papersubstrate made of paper, paper sheet or paper board; and at least afibrous absorbent layer formed on at least one surface of said papersubstrate for absorbing moisture or oil as vaporized or released from afood as contacted with the surface of the food container and as storedin the food container; said fibrous absorbent layer comprising amulti-component fiber including at least a biodegradable polymer and areinforcing polymer.
 2. A food container according to claim 1, whereinsaid fibrous absorbent layer includes a non-woven fabric or woven fabricmade from said multi-component fiber.
 3. A food container according toclaim 1, wherein said biodegradable polymer is selected from the groupconsisting of: polylactic acid (PLA), polyhydroxyalkanoate (PHA),polyhydroxybutyrate-co-valerate (PHBV) and Copoly-L-Lactide (CPLA).
 4. Afood container according to claim 1, wherein said reinforcing polymerincludes a thermobondable polymer, which includes polyethylene (PE), andpolypropylene (PP).
 5. A food container according to claim 1, whereinsaid fibrous absorbent layer is coated on said paper substrate by anadhesive or a binder.
 6. A food container according to claim 5, whereinsaid adhesive is a thermally bondable adhesive or a heat adhesive.
 7. Afood container according to claim 6, wherein said adhesive includespolylactic acid and polyethylene.
 8. A food container according to claim1, wherein said paper laminate further includes a protective film layercoated or formed on at least one side or one surface of said papersubstrate.
 9. A food container according to claim 8, wherein saidprotective film layer includes a heat stable and biodegradable polymer.10. A food container according to claim 9, wherein said polymer includespolyethylene blended with polylactic acid.
 11. A food containeraccording to claim 1, wherein said fibrous absorbent layer is furtherincorporated therein with a nano silver ingredient or an anti-bacterialingredient.
 12. A food container according to claim 1, wherein saidfibrous absorbent layer is further perforated to make it capillarilypenetrable by oil and moisture.
 13. A food container made of a paperlaminate comprising: a paper substrate; and a protective film layerformed on at least one side or one surface of said paper substrate; saidprotective film layer including a thermobondable polymer and abiodegradable polymer co-extruded or laminated to form said film layer.14. A food container according to claim 13, wherein said thermobondablepolymer is polyethylene.
 15. A food container according to claim 13,wherein said biodegradable polymer is selected from the group consistingof: polylactic acid (PLA), polyhydroxy alkanoate (PHA), polyhydroxybutyrate-co-valerate (PHBV), and Copoly-L-Lactide (CPLA).